<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
	<meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0, user-scalable=no" />
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>VH</title>
</head>
<body>
<style>
	.div {
		height: calc(100vh - 16px);
		background-color: #000;
		
	}
	.next {
		height:calc(100vh  / 2 - 20px);
		background-color: #f00;
		
	}
</style>
<div class="div">
	<div class="next" color="#00f"></div>
</div>
<style type="text/css">
input {background-color: expression( (new Date()).getHours()%2 ? "#F00" : "#00F" ); }
</style>
<input type="text">
<input type="text">
<input type="text"> 
</body>
</html>